Journal Article

PreJuSER-21990

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Environmental changes in northern New Zealand since the Middle Holocene inferred from stable isotope records (d15N, d13C) of Lake Pupuke

Heyng, A. M. ; Mayr, C. ; Lücke, A.FZJ* ; Striewski, B. ; Wastegard, S. ; Wissel, H.FZJ*

2012
Springer Science + Business Media B.V Dordrecht [u.a.]

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Please use a persistent id in citations: doi:10.1007/s10933-012-9606-5

Abstract: Maar lakes in the Auckland Volcanic Field are important high-resolution archives of Holocene environmental change in the Southern Hemisphere mid-latitudes. Stable carbon and nitrogen isotope analyses were applied on bulk organic matter and the green alga Botryococcus from a sediment core from Lake Pupuke (Auckland, North Island, New Zealand) spanning the period since 7,165 cal. year BP. The origin of organic matter was established using total-organic-carbon-to-nitrogen ratios (TOC/TN) as well as organic carbon (delta C-13(OM)) and nitrogen (delta N-15) isotope composition of potential modern sources. This approach demonstrated that the contribution of allochthonous organic matter to the lake sediment was negligible for most of the record. The sedimentary TOC/TN ratios that are higher than Redfield ratio (i.e. > 7) are attributed to N-limiting conditions throughout the record. Variations of nitrogen and carbon isotopes during the last 7,165 years are interpreted as changes in the dominant processes in the lake. While epilimnetic primary productivity controlled isotope composition before 6,600 cal. year BP, microbial processes, especially denitrification and methane oxidation, caused overall shifts of the delta N-15 and delta C-13 values since the Mid-Holocene. Comparisons with climate reconstructions from the Northern Island suggest that changes in the wind-induced lake overturn and a shift to more pronounced seasonality were the most likely causes for lake-internal changes since 6,600 cal. year BP.

Keyword(s): J ; Carbon (auto) ; Nitrogen (auto) ; Stable isotopes (auto) ; Lacustrine sediment (auto) ; Organic matter (auto) ; Botryococcus (auto) ; Paleoenvironment (auto)

Note: We thank Gillian Turner and Jim Neale for coring, Markus Oehlerich and Laurentius Sauer for assistance in the isotope lab, Alexander Altenbach for discussions. Thomas Stephens, an anonymous reviewer and the editors Thomas Whitmore and Steffen Mischke provided useful comments on an earlier version of this manuscript. Funding to AL and CM by the German Research Foundation (grant nos. MA 4235/1-1 and LU 786/5-1) is gratefully acknowledged.

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Contributing Institute(s):

1. Agrosphäre (IBG-3)

Research Program(s):

1. Terrestrische Umwelt (P24)

Appears in the scientific report 2012

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Database coverage:
; BIOSIS Previews ; Current Contents - Agriculture, Biology and Environmental Sciences ; JCR ; NCBI Molecular Biology Database ; Nationallizenz ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection ; Zoological Record

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